Crystal detector



June 21 1927.

H. C. ADAM CRYSTAL DETECTOR Filed March 1923 lab Z'/-/ VEN r02 Ham 6'. (7/4/17.

Patented June 21, 1927.

UNITED STATES HARRY C. ADAM, OF ST. LOUIS, MISSOURI.

CRYSTAL DETECTOR.

Application filed March 12, 1923. Serial No. 624,521.

This invention relates to devices that are used for receiving wireless signals, and particularly, receiving devices of the kind that are commonly referred to as crystal detectors.

One type of crystal detector that is now in general use consists of a crystal of galena or other mineral having rectifying properties, a metallic holder for said crystal to which one side of an electric circuit is con nected and a contact connected to the other side of said circuit and adapted to be arranged in engagement with the crystal so as to complete the electric circuit which the detector controls. Owing to the fact that the crystal consists of a piece of mineral composed of particles that have rectifying properties and particles that are non-rectifying, it is necessary to use a contact that has a. very fine terminal or end and construct said contact in such a way that it can be adjusted or moved over the crystal until the terminal of the contact touches a rectifying particle of the crystal, the contact usually being formed from a piece of fine wire connected to a finger piece that can be manipulated to adjust the contact relatively to the crystal. In using a crystal detector of the kind referred to it is often difficult to set the contact at a point on the crystal where the device will function properly, and another objectionable characteristic of such a detector is that a slight jar or jolt is apt to change the relationship between the terminal of the contact and the "crystal, thus necessitating readjustment of the contact.

I have discoveredthat if a crystal or piece of mineral having such properties as to perrnit of its use in a detector for receiving 4 wireless signals is crushed or divided into small particles and one of said particles that has rectifying properties is then arranged between two contacts or electrodes of materially greater area than said particles, that a detector will be produced which has not the objectionable characteristic of requiring delicate adjustment of one part of the device to insure the device functioning properly.

M) The particular shape, size and design of the contacts or electrodes are immaterial and the kind and size of the piece of rectifying substance that is interposed between said contacts is also immaterial, but a very satisfactory crystal detector can be produced by arranging a small piece of rectifying material, even, as small as the head of a pin or smaller, between contacts or electrodes of materially greater area that are arranged in theelectric circuit of an apparatus for receiving wireless signals," said piece of rectifying material being in contact with saidelectrodes and supported by the same.

Figure 1 of the drawings is a vertical sectional view of a crystal detector constructed in accordance with my invention.

Figure 2 is an elevational view, illustrating another form of my invention.

Figure 3 is a vertical sectional view, taken on the line 3 3 of Figure 2; and

Figure 4 is a side elevational view of the resilient element of the detector shown in Figures 2 and 3.

Referring to Figure 1 of the drawings, 2i designates a base piece formed preferably of insulating material, B designates two contacts or electrodes secured to' said base piece and adapted to be arranged in the electric circuit of an apparatus for receiving wireless signals, and C designates a small particle of material having rectifying properties that is arranged betweenthe contacts B in engagement with and supported by the same. Each of the contacts B preferably consists of a flat strip of metal that has some resiliency and said contacts are mounted on the base piece A in such a way that the upper end portions of same will be in opposed relation and will exert a slight pressure on the rectifying substance C that is interposed between them. If desired, the contacts B can be arranged vertically on the base piece A and positioned at opposite sides of a cup D that is arranged underneath the upper end portions of the contacts between which the rectifying particle C is positioned, thus forming adctector composed. of two contacts or electrical. conductors of relatively great area that are held in spaced relation by a particle of rectifying material of materially less area than said contacts, and a device D arranged in such a position that it will receive the rectifying particle C in the event it becomes displaced from its normal operative position between the contacts B. The contacts B are connected to the supporting base A by fastening devices 1 that can also be used for connecting said contacts to the opposite sides of the electric circuit, in which the detector is arranged.

The detector shown in Figures '2, 3 and 4 embodies the same desirable ClltllflCtl'lStlCS as the detector shown in Figure 1 and 1S composed of two contacts or electrodes E v 4 of the member E and the resilient central portion 4 of the member F, as shown in contact E.

and F of relatively great area and a small partlcle of. material G havlng rectlfying properties, interposed between said contacts 111 engagement; with the same and retained in position by a slight resilient pressure eX-' erted on said particle G by oneof said contacts. The contact E consists of a rigid di'skshaped metal member provided at its lower end with a bracket 2- that is connected me ha e or supporting structure H by a fastening device that can also be used as a binding post for one side of the circuit in Whichthe detector is arranged, and the contact F preferably consists of a limber conducting member that has a flexible or resilient central portion 45*. The rectifying substance G is positioned between the boss Figure 3. The member F is protected by a hous ng I or coverwlnch is retained inposition by fastening devices 5 which pass through said cover and member and are screwed into the disk-shaped member E.

The member F isinsulated from the memher E by an annular insulator 6 arranged be tween said parts at the peripheral edge of the member F and a soft annular insulator 7 that surrounds the boss 4 on the inner side of the member E, the portions of the fastening device 5 that pass through the cover I and member F being surrounded by insulators 8, so as to insulate said fastening devices from said cover and member In the. form of my invention herein shown the other side of the electric clrcuit n which i the detector is arranged is connected to the cover I and member F by a screw or binding post 9 that is screwed into the cover I and member F, as shown in Figure In a detector of the construction above described the rectifying particle G holds the central portion 45* of the member F spaced away from the boss L on the member E and the soft annular insulator 7 that surrounds the boss 4- serves as a .means to prevent said rectifying particle from becoming displaced or moved out of engagement with the'two contacts of the detector VVhile I have herein illustrated two different forms of my invention, 1 wish it to be understood that mv-broad idea consists of a so called crystal detector for receiving wireless signals that composed of two contacts or electrodes of relatively great area and a particle of rectifyingmaterial of. i

materiallylessarea than the opposed faces of said contacts interposed between the same in engagement therewith and supported by said contacts.

Having thus described my invention, what I claim as new anddesi're to secureby Letters Patent is z crystal detector composed of two substantially disk-shaped conducting mem bers arranged in parallel relation, one of said members being rigid and the other member being relatively limber and having a flexible or resilient central portion, a small-sized particle of material having rectifying properties inter-posedbetween .said resilient portion and the opposed part of the rigid member, an insulating means positioned between said members and a housing arranged in overlapping relation withsaid lunber member and secured to sald TlglCl member.

2. A crystal detector composed of a rigid conducting member, of substantially disk form arranged in an upright position and provided at its center with a boss, a co-operatinglimber member arranged at one side of: said rigid member in parallel relation with same and provided with a substantially spiral slot so as to form a flexible or resilient central portion that is disposed oppositely to the boss on the rigid member, a smallsized particle of material having rectifying properties interposed between said bossand resilient centralportiori, means arranged at the center and at the outer edges of said members for insulatii saidmembers from each otl on and adislt shaped cover extend-- ing over said 'limber member and. secured to said rigid member.

HARRY o. ADAISL 

